1. Field of Technology
This invention relates generally to pavement grinder machines, and more particularly to machines for cutting periodic depressions in road pavement, or rumble strips.
2. Prior Art
It is commonplace to have means on highways that alert drivers that their vehicle has drifted outside of a normal travel lane. One means of doing so is a series of periodic depressions in road pavement alongside a normal travel lane. These periodic depressions are commonly termed xe2x80x9crumble stripsxe2x80x9d because of the effect on a vehicle running over the depressions.
Machines have been disclosed that cut these rumble strips. Commonly, these machines comprise one or more lobed rolling wheels supporting the machine as it travels along the road causing the machine to move up and down with the lobes. A grinder brush below the machine penetrates into the pavement on lobe lows and lifts above the pavement on lobe highs. Although functional, with the full weight of the machine cycling up and down on its wheels, the machine is difficult manage and the continuous jarring exacerbates maintenance requirements. A machine that rolled normally on round wheels would obviate or reduce many of these requirements. Prior machines based on round rolling wheels have been large and complex and thus also costly and difficult to maintain, making them commercially less effective.
One object of the present invention is to provide a rumble strip cutting machine that rolls along a road smoothly, all ground engaging elements being round to limit weight shifting within the machine. Another object is to drive a vertically-oscillating grinder brush by measured movement of the machine along the road. Another object is to provide an oscillating frame within a smoothly-traveling, nonoscillating main frame that travels smoothly along the road. It is a further object that the oscillating frame, or moving frame, be driven by a crank action on a crankshaft internal the machine. It is yet another object that the crank action be driven solely by rotation of a round, ground-engaging wheel, preferably a support wheel. It is a further object that the machine be compact, of size comparable to an engine driving the grinder brush, along with attendant peripherals. It is another object that the machine be towable. It is a still another object that the ground-engaging wheels supporting the machine during operation be lifted from the ground during nonoperational transport, supported on a plurality of auxiliary wheels more conducive to highway travel speeds. It is a final object that the machine cut repetitive and periodic pavement depressions of uniform size and spacing.
These objectives are achieved in a rumble strip cutter machine comprising a nonoscillating main frame of generally rectangular configuration supported on round, ground-engaging operational support wheels. For nonoperational transport at highway speeds the main frame is lifted off of its operational support wheels by a pair of hydraulically-actuated auxiliary wheels at the main frame rear end, pivotable on support bars from a stored position during machine operation to a support position in which the rear operational support wheels are lifted off of the ground by the auxiliary wheels. The front operational wheels are lifted off the ground by rotating and locking a trailer tongue on the main frame front end toward the frame. To lower the front operational wheels into engagement with the ground, the trailer tongue is rotated away from the main frame by extending a hydraulic cylinder, urging the trailer tongue away from a front wheel axle while pivoting on a tongue pivot pin on a tongue upper portion at the main frame front.
An oscillating moving frame also of generally rectangular configuration coplanar within the main frame in a rest position moves slightly out of the common plane during its oscillatory motion. The moving frame oscillation is driven by crank and crankshaft action. A crankshaft is rotated solely by a mechanical arrangement of axles and gears driven by a ground-engaging wheel, preferably a front operational support wheel. A rod connects between the crank and the moving frame front end. With the moving frame rear end pivotably connected to the main frame rear end approximately over rear operational support wheels, pivotably lifting and lowering of the moving frame front end compacts an effective length of the machine with maximum moving frame movement at its front end.
A grinder brush is mounted central under the moving frame between the frame pivot pin and the crank lift position allowing an effective compact design while maximizing leverage effect by lifting with the crank at the moving frame front, most distant from the pivot pin, the crank lifting maximum weight with minimum materials strength and corresponding weight and allowing the ground engaging wheel to provide the sole drive for lifting the inner frame without need of auxiliary lifting mechanisms. An engine power plant is mechanically connected to the grinder brush through an arrangement of pulley belts or chains. The weight of the engine, mounted on the inner frame directly over the grinder brush, urges the grinder brush into the pavement. With the engine also mounted central the inner frame, the lifting effect of the crank is also maximized, as described above.